Wood Handbook, Wood as an Engineering Material

(Wang) #1

accredited consensus review processes involving users, pro-
ducers, and general interests. Then, commercial wood com-
posites are manufactured to conform to these commercial
product or performance standards (Table 11–2). These prod-
uct or performance standards are cited in the International
Building Code (IBC) and other similar documents. The IBC
is the model building code produced by the International
Code Council (ICC), a non-profit organization established in
1994 dedicated to developing a single set of comprehensive
and coordinated construction codes. Since the adoption of
the first edition of the IBC in 2000, most building codes in
the U.S. are based on the IBC. Previously, there were three
model code organizations that produced model codes with
largely regional acceptance. The ICC also produces the In-
ternational Residential Code (IRC) and other related model
code documents.


The ICC–Evaluation Service (ICC–ES) issues advisory
reports on their evaluation of building products, compo-
nents, methods, and materials for their compliance with the
IBC. The ICC–ES was created in 2003 with the merger of
the four existing evaluation services. ICC–ES also issues
ICC–ES Acceptance Criteria documents for specific types
of products that specify the performance criteria and the
data that needs to be submitted for the evaluations. These
evaluation reports and the acceptance criteria documents are
available on the web site of the ICC–ES (www.icc-es.org).


Types of Product Standards


Product standards may be classified as manufacturing
standards or performance standards. The best example of a
manufacturing method standard is Voluntary Product Stan-
dard PS 1–07 for construction and industrial plywood (NIST
2007). Specifications in the standard include which wood
species and grades of veneer may be used, what repairs are
permissible, and how repairs must be made. Limited per-
formance-based evaluations may also be specified in manu-
facturing standards for issues relating to adhesive durability
and strength.


Standard PS 2–04 (NIST 2004) is a performance-based
standard because it applies to all structural-use wood-based
panels, including plywood and OSB. This standard includes
performance requirements and test methods suitable for a
given application (qualification) and also require that prop-
erties of a qualified product remain in control during pro-
duction over time (certification). With respect to plywood,
the PS 2–04 standard is not a replacement for PS 1–07,
which contains necessary veneer-grade and adhesive-bond
requirements as well as lay-up provisions, but it is broad
enough to also include many plywood grades not covered
under PS 1–07. PS 2–04 specifies that certification be per-
formed by an independent third party.
The American National Standards for particleboard and
MDF (ANSI A208.1 and A208.2 respectively) are sponsored
by the Composite Panel Association (CPA) in Leesburg,
Virginia (CPA 2009a, b). These performance standards
require the composite products to show certain minimally
acceptable physical and mechanical properties. The test re-
quirements give some indication of product quality, but the
tests were not specifically developed to correlate with per-
formance of whole panels in specific end uses.
Role of Standards in Construction
Conventional wood-based composite panels and lumber ele-
ments manufactured in conformance with product standards
(Table 11–2) are approved under the International Build-
ing Code. These wood-based composites can be used for
construction applications such as sheathing for roofs, sub-
flooring, and walls. Similarly, many types of wood-based
composite lumber can be used for joists, purlins, stringers,
beams, and columns.
Design properties and basic installation guidelines of
structural-use panels have become standardized by the ICC.
The ICC requires independent third-party certification of
these panels, and several such third-party certification agen-
cies exist, such as APA–The Engineered Wood Association
(www.apawood.org) and TECO (www.tecotested.com).
These agencies and others offer a variety of technical infor-
mation on the proper selection, design, and installation of
structural-use panels.
Plywood panels conforming to PS 1–07 are marked with
grade stamps (Fig. 11–6a,b). Flake-based composites, such
as OSB, are usually marketed as conforming to a product
standard for sheathing or single-layer sub-flooring or un-
derlayment and are also marked with grade stamps (Fig.
11–6c,d).
Structural-use panels are also span-rated. Span ratings re-
fer to on-center spacing of support members (expressed in
inches), with the long panel dimension (in plywood this is
the same direction as the face grain) placed across the sup-
ports, assuming that there are at least two spans (a minimum
of three supports). Span-rating of construction plywood
and OSB simplifies materials specification in light-frame

Figure 11–13. Medium-density fiberboard with veneer
overlay. Edges can be shaped and finished as required
by end product.

General Technical Report FPL–GTR– 190
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